Process of producing a textile product



latented Mar. 18, 1947 UNITED STATES PATENT OFFICE rnocess or rnonucmc A'rax'rrha rnonvc'r Worth Wade, New York, N. Y., assignor to AmericanViscose Corporation, Wilmington, Del., a

corporation 01 Delaware No Drawing. Application December 8, 1943, SerialNo. 513,495

4 Claims.

This invention relates to fibre preparation and in particular to theproduction of potentially adhesive artificial filaments and to textileproducts tentially adhesive fibres in the mixture tacky tov bind thefibres in the product. When the potentially adhesive fibres in suchproducts are activated to render them tacky, for example, by theapplication of heat and pressure, the potentially adhesive fibres aredeformed by the pressure, and

if the heat is sufiicient the fibres may in whole or in part lose theirfibre shape and identity as fibres. This is due to the fact that thepotentially adhesive fibres heretofore used in the products disclosed inthe patents above-mentioned have been in every case of a homogeneouscharacter. However, it is frequently desirable that the fibres be lesssusceptible to loss of shape and that they retain their identity asfibres in the product after activation, since the loss of the fibrousform results in a decrease in strength. Moreover, with homogeneousfibres it is difficult to control the extent of the activation wherebythe fibres are rendered tacky but not destroyed. Another disadvantage ofthe prior potentially adhesive fibres lies in the fact that when formedof thermolastic materials, such as thermoplastic cellulose derivativesand thermoplastic resins, the fibres are susceptible of activation eachtime the textile product is treated by heat and pressure, and if thefibres have a low thermotacking point, they will become activated eachtime the textile products are ironed. This is a distinct disadvantagesince the repeated activation tends to stiffen the textile product andto render the fibres somewhat more brittle.

Therefore, it is an object of this invention to produce a filament whichis activatable by heat to an adhesive condition and which is lesssusceptible to loss of shape and of its identity as a filament duringactivation.

It is a further object to provide such filaments that their activationby heat is very easily and reliably controlled. The invention alsocontemplates a filament which can be coalesced or distorted by pressurewithout danger of severing the filament.

A further object is to produce a textile product containing athermoplastic filament which can undergo repeated activation withoutprogressivelyv deteriorating to such an extent as to lose its shape andidentity as a filament.

A specific object is to provide a textile product havingheat-activatable filaments therein which, during an initial activation,are caused to be first activated, then permanently set and therebybecome no longer subject to activation.

A further object is to provide an activatable filament having anexterior which is repeatedly activatable and having a core adapted to bepermanently set during the first stage of activation.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

According to the present invention, there is provided a filament whichis activatable by heat to an adhesive condition, the filament comprisingat least two portions composed, of different materials, one beingexterior to the other and forming the filament surface, the exteriorportion being an organic thermoplastic material more susceptible toactivation than the other portion. In the now preferred embodiment thecomposite filament of the invention comprises a more and a sheath, thesheath being an organic thermoplastic material more susceptible toactivation than the core. When both portions are activatable, they areso constituted as to be activatable under different conditions. Theinvention also provides an activatable fibre having a thermoplastic coreand a thermosetting exterior in which the thermoplastic core is merelysoftened without becoming fiuid at the temperature of activation of thethermosetting exterior, whereby the sheath produced during the initialactivation serves to stabilize the textile permanently by adhesionduring activation and thereafter serves to contain the thermoplasticinterior regardless of later conditions of treatment of the fabricconstituted thereof.

In the following detailed description and in the appended claims theword filament when referring to the potentially adhesive filaments,includes both continuous filaments and cut staple fibres; the expressiontextile includes yarns, fabrics, felts and papers, and the expressionactivating designates that operation by which the potentially adhesivefilaments are caused to bind filaments in the product.

The boundary between core and sheath portions may be quite distinct andeither of regular or irregular contour, or there may be a partial mixingor difiusion of one of such materials with the other at their juncture,or, again, there may be one or more layers of other materials betweenthe interior core and the exterior portion of the fibre or filament. Acore portion of composite character, as well as a sheath portion ofcomposite character are within the purview of the invention. A

Examples of thermoplastic materials which may be used in the core or thesheath are thermoplastic cellulose esters as a class, such as celluloseacetate; cellulose butyrate and propionate, suitably pla'sticized to athermoplastic 1 condition; thermoplastic cellulose ethers. as a' class,such, for example, as ethyl cellulose; propionyl cellulose; butylcellulose and benzyl cellulose; also thermoplastic mixed esters andmixed others and ether-esters of cellulose; thermoplastic syntheticresins, including polyvinyl resins and polyacrylic resins as well asderivatives thereof, such as polyvinyl chlorides; polyvinylidenechlorides; polyvinyl acetates; polymers of methyl or ethyl acrylates ormethacrylates; polystyrene;

copolymers of two or more polymerizable unabove.

' swelling and shrinkage tendencies, but which are saturated compounds,such as the copoiymer of vinyl chloride and vinyl acetate; or vinylchloride and acrylonitrile; of vinyl chloride and ethyl methacrylate;also after-chlorinated polyvinyl chlorides; and after-chlorinatedcopolymers of. vinyl acetate and vinyl chloride; and natural andsynthetic rubber. I

For the thermosetting materials which are used initially in thethermoplastic state and therefore capable of use in the presentinvention, there may be employed, for example phenol-aldehyde resins,urea-aldehyde resins, phenolfurfural res ins, urea-aldehyde-alcoholether resins, melamine-aldehyde resins and other amine-aldehyde resins;sulfonamide-aldehyderesins, alkyd resins, drying-oil-modified alkydresins, and the like.

If desired, a mixture of two or more of the. thermoplastic materials, ora mixture of two or more thermo-setting (initially thermoplastic)materials or a mixture of thermoplastic and thermosetting materials maybe used for either the core or sheath of the filaments and fibres.

In one embodiment, the core may be composed of a non-thermoplasticmaterial'such, for

example, as regenerated cellulose, gelatine,

casein, chitin, and the like, and may be provided with a sheath composedof or comprising a thermoplastic material or a thermosetting maintofilaments. Alternatively, the sheath may be formed of a filament-formingmaterial, while the core may be of a material incapable of formingfilaments. Advantageously, both core and. sheath are formed offilament-forming materials The composite thermoplastic filaments of the.

present invention may be produced by any suitable process, for example,by (a) applying a coating or sheath about a central core portion,

or by (b) extruding one material about a preformed core of'the other, orby (c) simu1taneously extruding the core and the sheath into a'commoncoagulating medium.

Filaments of special characteristics may be obtained by associating twodifferent materials as the core and sheath thereof, both of which areactivatable but at difierent temperatures or Thus, a thermoset-' underdifferent conditions. ting core may be associated with a thermoplasticor thermosetting sheath, while a thermoplastic core may be associatedwith a thermoplastic or thermosetting sheath. Preferably the sheath ismore susceptible to. the desired activation treatment. With activationby heat, the sheath becomes adhesive at a temperature lower than theentirely overcome by the application of a thermoplastic or thermosettingmaterial as a sheath about the core. Thus, a regenerated cellulosefilament or fibre which is highly hydrophilic and susceptible toswellingand shrinkage tendencies in thepresence of high humidity or when wet,may be waterproofed by a sheath of a thermoplastic resin, such as acopolymer of vinyl chloride and vinyl acetate, which at the same timeserves to make the filament activatable. The

same core material of regenerated cellulose may with or withoutpressure, as by passing dry hot air through the products, or by passingthe products through heated calender rolls or pressing them betweenheated plates; (2) by treating the fabric, with or without pressure,with moist heat I as by the use of hot water or steam. The use of steamin accordance with the procedure described and claimed in my copendingapplication Serial No. 444,438, filed May 25, 1942, is particularly Iadvantageous when it is desired to produce, soft or thick products; (3)by the application of radiation, with or without pressure, for example,by exposing the products to infra-red radiation of such intensity andduration as to activate the thermoplastic fibres; (4) I by subjectingthe fibrous products to high frequency induction field, with or withoutpressure, whereby the relatively nonv activating thermoplastic fibresare activated by the heat generated therein, and to promote such highfrequency induction heating of the potentially adhesive fibres, a minorproportion of an electrically conducting substance, such as metallicpowder, graphite, and the like, may be incorporated in the potentiallyadhesive fibre; (5) by the application, with or without pressure, to thefibrous product of a liquid which is a solvent or 'a softening agent forthe potentially adhesive fibre and simultaneously or thereafter heatingthe product, whereupon the potentially adhesive fibres are softened andrendered tacky after which th liquid agent may be removed if desired.

Activation of the yarns or fabrics may be accompanied by the applicationof pressure which has the efiect of increasing the number of points andareas of contact between the activatable fibres and themselves, orbetween themselves and the non-activatable fibres in the articleswhatever the case may be. The total number of the individual points ofadhesion and the total area constituted thereof in va. given fabric maybe predetermined by adjusting the proportion of fibre which isactivatable in the initial fibre mixture to be spun, or the Proportionof activatable continuous filaments in the initial continuous filamentyarn. Further variations and further opportunities to control the extentof the connection between the points of intercrossing of the yarns inthe fabric are obtainable by alternating one or more activatable yarnswith one or more non-activatable yarns in the weft or in the warp of awoven fabric, or on the successive courses of a knitted fabric.Similarly, in doubling, netting, braiding and knitting, one or moreactivatable yarns may be combined with one or more nonactivatable yarns.

Depending upon the particular desideratum in the final fabric to beproduced, the percentage of activatable fibres or filaments therein maybe varied widely. For simple stabilization of the fabric, a range ofactivatable fibres between 5 to 25% of the entire weight of the fabricis generally adequate, the balance being non-activatable. Whereconsiderable stiffening of the fabric is also desired, higherpercentages up to 100% of acti-' vata-ble fibre may be present in thefabric.

The activatable, filaments, either in the form of continuous filamentsor staple fibres, may be associated with non-activatable fibres orcontinuous filaments of any sort, such as regenerated cellulose fromviscose or cuprammonium cellulose, cotton, silk, wool, flax, kapok,casein, mineral fibres including asbestos, glass fibres, rock wool andthe like, for the production of textiles in accordance with the presentinvention.

The composite filaments thus formed are capable of employment ascontinuous filaments or cut staple fibres to advantage in the textilearts in numerous ways. In the making of textile yarns and fabrics,staple fibres cut from the thermoplastic filaments of the presentinvention may be used alone or in admixture with other activatableand/or non-activatable fibres, in the production of textiles of allkinds, such as yarns, fabrics and felts. The twist, hand and bulkcharacteristics of the yarns so formed may be set and stabilized byactivation of the thermoplastic filaments. Such yarn, either before orafter activation, may be woven, knitted or braided into fabrics, and thefabric will be stabilized by the adhesion between fibres in the yarnsand/or between yarns. Similarly, such yarns, either before or afteractivation, may beplied together or with other yarns whether activatableor not, into cords and the plying may be followed by activation orreactivation to set the twist and structure in the cord. Similarly,yarns which are formed of the continuous composite filaments may beformed of, or contain, the composite activatable continuous filaments ofthis invention, and these continuous filament yarns may be fabricatedinto cords by plying, into textile fabrics by weaving, knitting,braiding, netting or felting, after which the fabrics may be activatedto stabilize the structure.

Textile fabrics, whether knitted or woven, braided or plied, can thus beproduced which are substantially free of any tendency of the componentyarns and filaments therein to slip with respect to the others, andparticularly in regard to knitted fabrics, free of any tendency to runor ladder upon the breakage of one of the loops therein. It is alsopossible to control slippage and laddering to any predetermined extentby adjusting the extent of activation. Fabrics thus stabilized may becharacterized by the same high porosity and fullness of hand as suchfabrics before stabilization by activation of the yarns thereof. Ifdesired, activation may be so effected as to impart to the fabric astiffness which may be of special advantage in the production offabric-stiffening materials, particularly for collars, cuffs and thelike. Also,the activation may be effected in such a manneras to controlthe porosity of the fabric, and may be so extensive as to impart asmooth glossy surface to the fabrics.

The activatable filaments of this invention may be employed for theproduction of felts, either by the dry-laying or wet-laying processes.As in the applications mentioned above, the percentage of activatablefibres may vary from a very low proportion, such as 5%, up to of theproduct, and the extent of activation may be varied as desired to obtaina predetermined amount of porosity stiffness and density in the feltproduct. The activatable filaments of the present invention may beassociated with non-activatable filaments to produce numerous fibrousproducts applicable to various textile uses, such as hats and otherclothing, and also to industrial uses. For example, they may be appliedin the form of braids, felts, threads or cords, for use as packingmaterial and gasket material for sealing relatively moving or stationaryparts of machinery of any kind, or in similar form as wicks fortransmitting liquids to elements or surfaces to be lubricated orotherwise coated. The activatable fibres of this invention, with orwithout non-activatable fibres, may be fabricated into such articles asbattery separators, heat-insulation material, sound-insulation material,cushioning, padding, filtering materials either for gaseous or liquidsuspension,

etc.

By way of illustration, but not by way of limiting the invention, therewill be given the following specific examples:

Example 1 There is formed a'composite potentially adhesive filamenthaving a thermoplastic core and a thermosetting sheath. For the corethere is employed a filament-forming copolymer of vinyl chloride andvinyl acetate which has been afterchlorinated until its softening pointis about, C. Such a core isthen provided with a sheath comprising aurea-formaldehyde butanol ether resin in the thermoplastic state, theresin containing 5% of a suitable plasticizer and a, small percentage ofan ammonium salt as a curing catalyst. Fabrics made in whole or in partof such filaments are activated at temperatures below 125 C, withpressure, at which temperature the sheath becomes tacky but the coredoes not lose its filamentary form. During activation theureaformaldehyde butanol resin is polymerized to the infusible state sothat thereafter the fabrics may be ironed even at temperatures above thesoftening point of the core without, reactivation of the compositefilaments.

Example 2 There is prepared a potentially-adhesive filament comprising athermosetting core and a thermoplastic sheath by forming the core of aureaformaldehyde butanol ether resin in the fusible state containing 5%of a suitable plasticizer and a small percentage of a catalyst as'inExample 1,

7 fusible state. After the initial activation the core is no longerfusible so that the sheath ma be rendered repeatedly tacky withoutsoftening the core, thus avoiding repeated shrinkage of the compositefilament.

-Example 3 There is prepared a potentially adhesive filament comprisinga non-thermoplastic core and a thermoplastic sheath by forming the coreof viscose rayon and the sheath of suitably plasticized celluloseacetate. such composite filaments may be activated at any temperaturewhich renders the cellulose acetate sheath tacky without causing asoftening of the core. Thus, the fibre form of the filament isrefilaments and articles is retarded.

Example 4 There is prepared a composite potentially adhesive filament inwhich both the core and the sheath are thermoplastic but have diilerentthermal softening points, preferably the sheath softening at a lowertemperature than the core. Thus, the core may be formed of unplasticizedcellulose acetate softening at 120 C. and the sheath of polyvinylacetate having a thermal tacking point of 100 C. Thus, articles formedfrom such filaments may be activated to bind fibres therein by heatingto a temperature at which the sheath is rendered tacky but at which thecore is not softened, thus preserving the fibre form of the filament andpreventing breakage and distortion of the filament.

Example 5 y A fabric for use as a cover for ironing boards,

' for heat insulation, or for other purposes where l the fabric byre-activation of the sheath of the composite fibres.

Example 6 A composite potentially adhesive filament is formed using asingle nylon mono-filament as the core and having a sheath formed from a1 mixture of a thermoplastic'resin and a thermosetting resin; forexample, a mixture .ofthree parts of Bakelite phenol-formaldehyde resinand one part of a Vinylite polyvinyl butyral resin, the Bakelite resinbeing in the organic solvent soluble fusible state and containing asmall percentage of a latent acid catalyst and one-half part of aplasticizer such as FlexoP' plasticizer. Such composite filaments havethe property of being activatable repeatedly at moderate temperature,but upon prolonged heating or heating at more elevated temperatures thefilaments can be cured so that they are no longer activatable.

The composite filaments of the present invention and the textileproducts produced therewith Fibrous products made from Y I tained duringactivation and shrinkage of the are characterized by many unforeseenadvantages. The filaments are less susceptible to loss of the shape andidentity of the filaments durin activation, and the extent of activationby, heat can be more easily controlled than with homogeneous potentiallyadhesive filaments. A greater pressure or less control of pressure isrequired with the present filaments and products since there is lessdanger of the composite filament being severed during activation as aresult of being pressed against an adjacent filament. The filaments andarticles produced therewith are capable of being permanently set andthereby no longer subject to activation, which'is an advantage when itis desired to maintain the shape and structure of an article even atelevated temperatures.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A process of producing a textile product comprising forming 'astructure of composite, po-

tentially adhesive filaments comprising at least two integral portions,one of said portions being a core portion and the other being a sheathportion, exterior to and encasing said core portion and forming a smoothlongitudinally continuous and homogeneous filament surface, the coreportion being formed of organic material of non-cellular structure, andthe sheath portion being formed of a thermosetting resin in thethermoplastic state, heating said structure to cause the sheath portionsof adjacent filaments to soften and adhere to each other, and to causeinterpolymerization of the thermosetting resin comprising said sheathportions so adhered to each other, and continuing polymerization of saidthermosetting resin to the infusible state, whereby the filaments of thestructure are bonded to each other at the points of intercrossing, andthe bonds betwee. said filaments renderedtresistant to heat.

2. A process of producing a textile product in accordance with claim 1in which the core por' tion is formed of a. thermoplastic synthetic re.

3. A process of producing a textile product accordance with claim 1 inwhich the core pr. --tion is formed of anon-thermoplastic organmaterial.

4.v A proeessof producing a, textile product accordance with claim 1 inwhich the cor p0rtion is initially formed of a thermosetting resir. inthe thermoplastic state, the resin forming the core portion and theresin forming the sheath portion being polymerized to the infusiblestate.

WORTH WADE.

REFERENCES crrEn The following references are of record in the file ofthis patent:

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